Handling pulverized coal and the like



ug- 14, 1934- J. w. THOMAS v HANDLING PULVERIZED COAL AND LIKE Original Filed Aug. 3, 1927 i iw M VENTOR Patented Aug. 14, 1934 UNITED STAT-ES PATENT yQFFICE HANDLING PULVERIZED COAL THE LIKE John W. Thomas, Bethlehem, Pa., assignor to Oscar W. Jeffery and Harry G. Kimball, copartners, New York, N. Y.

Application August 3, 1927, Serial No. 210,218 Renewed November 14, 1932 3 claims. (o1. a02- 36) pulverized material (it may be in a more or less steady stream) into an air pipe or channel having a place where the material can collect, usually a rise, bend in a vertical plane, pocket, or other obstruction to the free and direct flow of the material but, like a rise or bend, permittingl the movement of the pulverized .material under sufficient thrust. Into the pipe or channel I blow air in insufcient volume and.

at an insuflicient velocity to carry the pulverized material freely through the place of collec- 'tion in suspension or otherwise, so that the material there settles. As thev mass of settling material grows in volume sufficient to form a plug or slug 'large enough to close the pipe or channel, I apply the air back of it with sufficient pressure to drive the mass forward through the pipe. The material travels the pipe or channel therefore, beyond the place of collection, in the `form of slugs of about equal sizes, each `separated from its neighbor by a body of compressed air and each compacted behind by the oncoming air and compacted in front by the pressure of the air in front of it and which is driving ahead the slugs in front of it. The slugs can be formed and started in motion entirely by the action of the obstruction and the air, e. g., the source of the air being such that the pressure in the pipe or channel between the obstruction and the air inlet rises as the material accumulates and impedes the free flowof the air, and falls sharply again as each slug starts to move forward; at the inlet into the pipe or channel, the'ar inflow may tend to have something of a constant velocity characteristic rather than a characteristic tending to maintain a constant pressure between the obstruction and the air inlet. Also the material can be deposited in a pocket or branch passage locally by-passed for the air, the collected masses being started in motion by intermittently closing the by-pass, so that intermittently the whole air flow and pressure is thrown back of the collecting pulverized material; with this last arrangement the air inflow may be such as to more nearly tend to maintain a constant pressure back of `the obstruction.

I have also found that a venturi provides an advantageous means for getting the pulverized material into compressed and traveling air, the transporting air, for example, entering by a terial according to my invention, I admit thel nozzle pointing through the venturi and the pulverulent entering through the annular space surroundingv the nozzle. While freely admitting the pulverulent material, the venturi form adequately resists and sustains the pressure of the air or mixture existing beyond the outlet of the venturi, and hence the vincoming Amaterial (as the mass in the bi'n from which the coal is drawn) is not called on to act as a seal to prevent discharge backwards.` Accordingly the supply b n may be aerated to cause the pulvery ized material therein to ilow freely and regularly. `The action, it will be observed, is substantially an injector action.

The accompanying vdrawing illustrates my invention diagrammatically, Fig. 1 illustrating substantially an arrangement I have used for conveying pulverized coal long distances by an overhead pipe line, and Fig. 2 being a section of a modification of the collecting arrangement.

In Fig. 1 a bin for pulverized coal is indicated at 1. It can be assumed that this is the main storage bin of the" plant into which the pulverized coal is delivered from rthe Crushers, and from which it is conveyed through the pipe 2 to burners or smaller bins adjacent the burners. A system of perforated pipes 3 supplied by air through pipe 4'serves to aerate the mass of coal in the bin. It will be understood however that the coal can be conveyed by my invention, even if not aerated. At 5 is a sliding valve to entirely close the outlet from the bin as occasion may demand. At 6 is a pair of intermeshing driven toothed wheels rotating in the directions of the arrows, for feeding or regulating the feed of the coal downwardly; these toothed wheels can be driven from any suitable source, of power at a speed dependent on the rate of coal feed desired. It will be remembered that thoroughly aerated pulverized coal tends to flow very freely as well as'regularly. From the feed or regulator 6 the coal comes to the entrance of a venturi 10. From a nozzle 11 air is blown through the venturi and carries along with it coal delivered to the entrance end of the venturi, this coal passing to the bend l2 and rise 13 of the :conveyor pipe 2 by which the coal is conducted to the receiver or receivers. All the transporting air, it will be observed, can be put in through the nozzle 11. As before explained, the air-flow beyond the venturi, is insufficient to carry the pulverized material freely through the bend 12 and rise 13. Accordingly, the coalsettles out in the bend or the rise or both, and collecting, tends to close the channel. It can be assumed that the source of air` (conventionally represented byl the pipe 14) is such as to tend to continue to deliver air through the nozzle 1l regardless of any increase in pressure in the conveyor pipe; that is to say, the source of air such as to rather tend to deliver air at a vconstant rate rather than in a manner to mainand as a slug travels the conveyor pipe 2 to an outlet. Assuming'that the coal is fed in continuously, it is obvious thatv these slugs will be formed one after another in substantially equal periods of time, and hence of substantially equal size and will follow one another through the conveyor pipe, each two slugs being separated by an air space.

By way'of-further illustration, I shall indicate relative sizes of the apparatus I have used and found eieetive: The length of the venturi was about eighteen inches and its smallest diameter about two inches; the smallest internal diameter of the air nozzle 11 was three-fourths of an inch. The diameter of the casing between the outlet of the venturi and the beginning of the bend 12 was about six inches, and from this six inch section the diameter of the conveyor` pipe was gradually reduced to four inches at the bottom of the bend and continued at four inches from there to the end. From the top of the six inch section to the bottom of the bend was about twelve inches. The rise 13 was a rise of about iiiteen feet vertically in a distance of about twenty feet measured horizontally. It will be understood that all the apparatus of which I have given the diameters, was circular in cross section. With such apparatus, I have transported pulverized coal in the manner described approximately one thousand feet.

Referring now to the by-pass form of slugformer of Fig. 2: As an incident, I have again shown intermeshing toothed wheels 6 for feeding or controlling the feedof the coal, an electric motor for driving them being indicated at 20; also, I have again shown the coal forced into the compressed air of the conveyor pipe by an injector type of apparatus like that of Fig. l; as before,the bin may or may not be aerated. From the outlet of the venturi, the coal and air passes to the two branched passages 2l and 22, the common entrance to which is the somewhat enlarged chamber 23. In the passage 21 is provided a throttle valve 24 which, in the present instance, is diagrammatically illustrated as opened and closed at regular intervals by the crank wheel 25 belt-driven from the motor 20. When the throttle valve 24 is open, the air flows freely through the passage 21and thence on through the conveyor pipe 2. However, in passing through the chamber 23, the pulverized coal, or a considerable part of it, falls out of the air, because of the expansion of the air at the outlet from the venturi and the reduction in velocity at this point. This coal falls into the passage 22 and there collects. Subsequently, when the rotation of the crank wheel 25 momentarily closes the throttle valve 24, the full pressure of the air is thrown onto this mass of coal which now (the closing of the throttle is so timed) more or less completely, lls the cross section of the 22, or at least the end of it nearer the venturi 10, and this air pressure thrusts the collected material forward as a unit, out of the passage 22 and beyond the outlet of pmage 21. Air following through both or one of the passages 21 and 22 carries it through the conveyor pipe 2 as before. Preferably, I make the passage 22 larger at its entrance end than at its outlet end; for example, the diameter at the point 26 may be, say, 50% greater than the diameter at the Vpoint 27, the latter not being less than the diameter of the balance of the conveyor passage 2. I believe it to be advantageous to collect the pulverized material in a passage somewhat larger than the conveyor passage, so that the expelled masses, are not only compacted by the pressure of the air ahead of and behind them respectively, but also by the gradual reduction in the size of the passage' or channel as they leave the point of collection. So long as the air ow through the venturi is adequate to draw in the coal, it is not so important with this type of slug-former that the air pressure be variable; inasmuch as the pressure to start the coal masses or slugs is imposed on the slugs by the closing of the valve 24, the air pressure may be maintained more nearly constant between the slug-former and the outlet of the venturi with this type of slug former.

It will be understood that my invention is not limited to the details illustrated and described, except as appears hereinafter in the claims.

What is claimed is:-

1. The combination of a venturi, an air nozzle delivering into the venturi, a source of pulverized material to be conveyed connected to the venturi, a conveyor leading from the exit from the venturi and provided with an obstruction to the free and direct flow of thematerial, and means providing a low of air through said nozzle of insuiiicient volume and velocity at the obstruction to blow the material past said obstruction continuously but capable of developing sufficient pressure back of a collected mass of the material at the obstruction to blow the mass past said obstruction.

' 2. For transporting pulverized material pneumatically to a remote point, the combination of pipe means through which the pulverized material is to be transported, means to deliver pulverized ,material to said pipe means in a substantially regular manner, said pipe means providing, adjacent said delivery means and between the latter and the outlet end of said pipe means, an obstruction to the free transportation of pulverized material suspended in `air flowing in said pipe means, and means to provide a continuous flow of air into said pipe .JOHN w. THOMAS.

'CERTIFICATE OF CORRECTION.

Parent No. 1,970,405. i' August 14, 1934.

JOHN W. THOMAS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 139, claim 2, for "derive" read drive; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office. A

Signed and sealed this 11th day of September, A. D. 1934.

Lesl ie Frazer (Seal) Acting Commissioner of Patents. 

